Permafrost thawing below shallow Arctic lakes
http://news.agu.org/press-release/permafrost-thawing-below-shallow-arctic-lakes/[font face=Serif][font size=5]Permafrost thawing below shallow Arctic lakes[/font]
16 June 2016
Joint Release
[font size=3]WASHINGTON, DC New research shows permafrost below shallow Arctic lakes is thawing as a result of changing winter climate.
Warmer winters combined with an increase in snowfall during the last 30 years have limited the growth of seasonal lake ice. In response, lakebed temperatures of Arctic lakes less than 1 meter (3 feet) deep have warmed by 2.4 degrees Celsius (4.3 degrees Fahrenheit) during the past three decades, and during five of the last seven years, the mean annual lakebed temperature has been above freezing.
These rates of warming are similar to those observed in terrestrial permafrost, yet those soils are still well below freezing and thaw is not expected for at least another 70 years. However, a regime shift in lake ice is leading to sub-lake permafrost thaw now.
Since permafrost underneath lakes is generally warmer than the surrounding terrestrial permafrost, rising temperatures in the lakebeds make permafrost thaw sooner than beneath surrounding dry land. These lakes may cover 20 to 40 percent of the landscape in vast areas of Arctic lowlands.
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